ABSTRACT The nematode, Caenorhabditis elegans, has been identified as a ?high connectivity? animal for cellular development. This very small simple animal has been widely adopted for experimental study due to its excellent genetics and accessible cell biology. The complete genome of the worm has been published, and most of the adult anatomy has been reconstructed from electron micrographs of serial thin sections. However, EM techniques are not widely utilized by the C. elegans community, and most previous EM data are not easily accessed except through the support of this grant. The Center for C. elegans Anatomy concentrates on 1) publishing detailed information regarding the anatomy of the nematode in the form of annotated TEM and light micrographs, available on our two websites WormAtlas (text-based) and WormImage (image database), and by ftp, on hard drives, and in book form as the C. elegans Atlas. The Center is 2) providing practical training in modern EM methods for students and postdoc's and 3) testing new EM methods for C. elegans. We also conduct new EM surveys of the wild type anatomy at key developmental stages to supplement the Atlas, and to fill in gaps in our general knowledge.